Update types.

types/lib/legacy/class.d.ts

@@ -91,7 +91,7 @@ declare namespace Polymer {
    *
    * @returns Generated class
    */
-  function Class(info: PolymerInit): {new(): HTMLElement};
+  function Class<T>(info: PolymerInit, mixin: (p0: T) => T): {new(): HTMLElement};
 }
 
 declare class PolymerGenerated {

types/lib/legacy/legacy-data-mixin.d.ts

@@ -0,0 +1,27 @@
+/**
+ * DO NOT EDIT
+ *
+ * This file was automatically generated by
+ *   https://github.com/Polymer/gen-typescript-declarations
+ *
+ * To modify these typings, edit the source file(s):
+ *   lib/legacy/legacy-data-mixin.html
+ */
+
+/// <reference path="../utils/mixin.d.ts" />
+
+declare class UndefinedArgumentError {
+}
+
+declare class LegacyDataMixin {
+
+  /**
+   * Overrides `Polyer.PropertyEffects` to wrap effect functions to
+   * catch `UndefinedArgumentError`s and warn.
+   *
+   * @param property Property that should trigger the effect
+   * @param type Effect type, from this.PROPERTY_EFFECT_TYPES
+   * @param effect Effect metadata object
+   */
+  _addPropertyEffect(property: string, type: string, effect?: object|null): void;
+}